There have been racist slurs, sexism, homophobia, more than the apparently allowable amount of bullying, and finally, over the weekend, an expulsion from the house. Which is the simple explanation for why the ratings might rise – it's like the way traffic slows down on the opposite side of the motorway after a pile-up. But there's also more to it than that …

Summer slump

Partly because there's just not much on TV in the US in summer, when the networks have traditionally aired comedy and drama repeats. And now reality TV, which is much cheaper to make that scripted shows. There's one night of the week at least where at least five of the major networks were all showing reality shows at the peak hour. And against things like America's Got Talent, which is OK - and More to Love, which is a version of The Bachelor for larger citizens - Big Brother has been able to hold its own. And more.

Different beasts

It's actually hard to compare the UK and US versions of Big Brother – the American one is a different beast entirely. It's a weird, weird beast.

There are lots of things that make a difference – the ridiculously large and plush house; constant high-prize games, with cash, holidays, sodding speedboats and things; everyone has shiny hair and there's $500k to play for at the end. But the main difference is who votes.

Strategy strategy strategy

Where Big Brother UK bans any talk of nominations – with occasional lapses in the hard-and-fast rule, as seen in the last couple of weeks – the US show is about nothing BUT nominations.

The public don't vote on the weekly eviction: the players do. The "Houseguests", as they're called, have several roles in the house to play for.

That of the Head of Household, who is the only person to nominate for eviction, in a special ceremony, and directly, to people's faces. There's also a power of veto, which can be won in a separate competition and used strategically to save one of the nominated ... or not. And then there are random other twists - just like in the UK version – and other powers and prizes.

And when you read the minute-by-minute reports and recaps, they read like someone commentating on a game of Risk, or Bridge, or even Dungeons & Dragons: "See, if person A now uses their special power to save person B, the allegiance they've been building with persons C and D will be broken, though the secret allegiance they've been building with persons B, X and Y will be both strengthened and revealed…"

So it's definitely a game; it's just more like the strategic gameplay and Machiavellian bits of the first couple of seasons of the UK version than the ones since people started realising the game was in playing for the cameras and the public.

The what-AREN'T-you-telling-me factor

With the three show a week format for the US version – making, in reality, under two hours of Big Brotherness – there's obviously a lot more editing that goes on for the main shows than for the nightly Channel 4 recaps.

But the live feeds are also available on the internet – unlike the UK, where this feature has been dropped – on a subscription basis. Which is great, in revenue terms, but causes a several-tier viewing experience.

So while the CBS shows are all neatly packaged with lots of flashbacks to back up producers' favourites and points they want emphasising; there are people that are watching what's been happening days before that on the live feeds and feeding it in turn into blogs and forums and Twitter.

So when, early on, one otherwise cuddly contestant used racially and sexually abusive terms in an argument and they were cut out of the TV footage – but the over-the-top reactions of the receiving end were used, tacked on to something else – there was uproar not only because the slurs were being allowed, unquestioned, but were edited out to show someone in a better light in the main programme.

It's not only that people know what CBS is not showing: they want to know why. And knowing how this works has fed back into the cast of the show as well.

Chima, yet another contentious and varyingly offensive houseguest – though, frankly, they none of them have much charm – was thrown out of the house this last week for damaging property, refusing to wear her microphone and ignoring Big Brother.

While in the house, however, she fought against the power of the producer, bringing up contentious points again, in full, during the one live show a week, and promising to go nuts in the live show last week if she didn't get her way. They ended up prerecording by several hours to avoid that. She wasn't well-liked, by the opposing clique of houseguests, individuals or by many of the audience. But it appears the main reason she's been thrown out of the Big Brother house is for causing trouble – in a house that was made to create it.

For all these differences, is the US version, with its petty cliques, power struggles, double-bluffs and shifting allegiances, closer to being the social experiment that Big Brother was originally hailed as than many of the other international versions?

It's not happy television, certainly: it's high-pitched and shouty and full of unpleasantness. But if this reflects the society the show exists in, and people are tuning in in undinimishing numbers to get a view on it - there might still be an argument for Big Brother's usefulness.

Or at least, its place above Dance Your Ass Off, which is one of the competing reality shows on US TV right now.